An R—Fe—B based sintered magnet represented by an Nd—Fe—B based sintered magnet is employed today in various fields because it utilizes inexpensive materials abundant in resources and possesses superior magnetic characteristics, however, since it contains a highly reactive rare earth metal: R, it is apt to be oxidized and corroded in ambient. Accordingly, in many cases, a corrosion resistant film is formed on the surface of the R—Fe—B based sintered magnet when in practical use. Various coating films such as a metal film, are known as the corrosion resistant films to be formed on the surface of an R—Fe—B based sintered magnet, and among them, a vapor deposited aluminum film is known to have not only excellent corrosion resistance, but also superior adhesion reliability with an adhesive (i.e., delamination hardly occurs between the film and the adhesive up to the intrinsic fracture strength of the adhesive) which is required in the case of embedding a component. Accordingly, the rare earth metal-based permanent magnets having a vapor deposited aluminum film on the surface thereof are used, for example, by embedding them in various types of motors (Patent Document 1)
However, the R—Fe—B based sintered magnet having the vapor deposited aluminum film on the surface thereof and being embedded in the motor of automobiles, which, among the various types of motors, is exposed to severe temperature change in its environment of usage. Thus, excellent adhesion strength with the adhered object is required to be maintained, for instance, even after the magnet is subjected to a heat cycle test in the temperature range of −40° C. to 120° C.; however, this requirement is not easy to achieve. This is mainly attributed to the fact that the R—Fe—B based sintered magnet exhibits anisotropy in thermal expansion and shrinking (more specifically, the thermal expansion coefficient is 6.5×10−6/° C. in the direction parallel to the direction of magnetization, and is −1.6×10−6/° C. in the direction perpendicular thereto). Thus, in the case an R—Fe—B based sintered magnet having a vapor deposited aluminum film on the surface thereof is subjected to a heat cycle test, the behavior of the R—Fe—B based sintered magnet according to the thermal history results differently from the behavior of the vapor deposited aluminum film formed on the surface of the magnet according to the thermal history; this causes a drop in adhesion strength due to the interfacial failure which occurs by the considerable deterioration in peeling strength ascribed to the strain and the stress generated at the interface between the magnet and the film. Accordingly, a method for solving such problems is demanded, but is yet to be proposed.    Patent Document 1: JP-A-2003-224944